Handling of paper pulp



Sept. 25, 1962 E. EBERHARDT 3,

HANDLING OF PAPER PULP Filed Sept. 9, 1957 2 Sheets-Sheet 1 INVENTOR.LEE E. EaERunRo-r ATTORNEY p 25, 1962 L. E. EBERHARDT 3,055,795

HANDLING OF PAPER PULP Filed Sept. 9, 1957 2 Sheets-Sheet 2 PULPSUSPENSION HTTR/T/o/v M ILL r 14- H? F c Hm 5WD FELTER PRE-CoMPREssoRLnv- Boy '2 I INVENTOR.

LEE E. EBERnnnor Bnu/vq- PREss BY BALE 0F PULP ATTORNEY 3,055,795HANDLING OF PAPER PULP Lee E. Eherhardt', Springfield, Ohio, assignor toThe Bauer Brothers Company, Springfield, Ohio, :1 corporation of (thinFiled Sept. 9, 1957, Ser. No. 682,874 12 Claims. (Cl. 162-400) Thisinvention relates to pulp handling systems and more particularly to anew and improved method and system for drying and baling pulp forstorage and shipment.

The most serious problems facing non-integrated mills are due to theinadequacy of available pulp handling systems and the diflicultiesattendant preparation of pulp for World-wide shipment in accordance withprior art methods. Conventional methods employed to prepare pulp forshipment require high capital and involve high operational costs.Moreover, they have a relatively narrow range of application and maycause degradation in end product quality.

Ground wood, for example, is one of the most versatile market pulps, yetthe marketing of this product has been severely handicapped because ofthe necessity of shipping it in a substantially liquified conditioncontaining about fifty percent solids. Shipment of ground wood in thisform may cause degradation due to microbiological deterioration over arelatively short period of time. The pulp resultingly loses most of itsvalue in shipment and requires considerable processing by the consumerto effect products of any quality. As is obvious, the high water contentof the pulp as conventionally prepared for shipment requires largevolume and high tonnage shipping capacity.

Many methods have been investigated in an eifort to obtain an effectivesystem for drying and baling pulp to reduce shipping and handlingproblems but they have been handicapped by high initial capital costs,high operational costs, and loss of quality in the end product, the endproduct usually being difiicult to re-pulp at the consuming mill.

The present invention atfords a solution to the above indicateddifliculties in the art. It provides a simple sys' tem for drying andbaling pulp that involves a low capital cost, dries the pulp to a highsolids content, reduces the unit volume required for shipping pulp, andworks the pulp to a form that can be handled with simple loading andunloading equipment. The invention system also prevents pulp degradationand effects a pulp which the ultimate consumer can readily re-pulpwithout difficulty. Moreover, the product of the invention method, asdelivered to the consumer, retains much of its original, inherent wetpulp strength.

A primary object of the invention is to provide a simplified andimproved method of preparation of paper pulp for storage and shipmentwhereby such method will produce substantial economy, be more eflicientand satisfactory in operation, be readily adaptable to a wide variety ofapplications and effect quality control of the pulp in the process.

A further object of the invention is to provide a simple, low capitalcost system for drying and baling pulp.

A further object of the invention is to provide an improved method ofdrying and baling pulp for shipment which effects a drying of the pulpto a high solids content.

Another object of the invention is to provide an improved method fordrying and baling pulp that reduces the pulp from considerable volume toa package or bale of a size that can be readily handled with simpleloading and unloading equipment.

An additional object of the invention is to provide an 3,@55,79 5Patented Sept. 25, 1962 improved system for drying and baling pulp forshipment that prevents contamination of the pulp in handling.

A further object of the invention is to provide a new and improvedmethod for drying and baling wood pulp for shipment that prevents pulpdegradation in the process and provides a pulp which can be readilyre-pulped by the ultimate consumer.

Another object of the invention is to provide an improved method ofdrying and baling pulp that causes the pulp to retain a maximum of itsoriginal, inherent wet pulp strength.

A further object of the invention is to provide a new and novel methodfor drying and baling pulp.

A further object of the invention is to provide a method and apparatusfor handling paper pulp possessing the advantageous structural features,the inherent meritorious characteristics and the mode of operationherein mentioned.

With the above primary and other incidental objects in view, which willmore fully appear in the specification, the invention intended to beprotected by Letters Patent consists of the features of construction,the parts and combinations thereof, and the mode of operation ashereinafter described or illustrated in the accompanying drawings, ortheir equivalents.

Referring to the drawings wherein are found some, but obviously not theonly forms of embodiment of the invention;

FIG. 1 of the drawings schematically illustrates a flow diagram of theinvention system for drying and baling pulps; and

FIG. 2 illustrates a modification of the system of FIG. 1.

Like parts are indicated by similar characters of reference throughoutthe several views.

The invention method and system can be best described with reference tothe flow diagram illustrated. In the practice of the invention a pulpsuspension consisting of wood fragments in a liquid carrier is initiallydelivered to a vacuum decker 10. Here a portion of the water or otherliquid carrier is separated from the pulp and drained off, leaving apulp of 15-20 percent solids. Some initial shredding of the pulp may beaccomplished at the decker depending on the type of removal deviceemployed.

From the decker, the pulp is carried through conveyor 11 which furtherdisintegrates the partially dewatered pulp so that it readily enters acontinuous press 1 wherein suflicient water is drained to increase thesolid content to 40-50 percent.

The de-watered pulp from the continuous screw press is then delivered toan attrition mill 12, either a single or double disc, or modified hammermill, wherein the pulp is fluifed and separated into individual fibers.The flufling action is accompanied by a flashing of moisture due to theemission of water vapor or steam in proportion to the attrition powerapplied in flufling. Accordingly, the percentage of bone dry solids inthe suspension delivered from the mill is thereby slightly increased.

From the flufling stage the pulp is dropped into a pneumatic conveyorand discharged into a heated :air stream provided by a flash drier 13.This drier preferably consists of a direct fired multiple pass rotatingdrum drier as indicated in the schematic drawing. The heated air streamcarries the pulp suspension from the flufling stage through the multiplepasses of the rotating drum. This process causes additional moisture tobe flashed in the air stream, dependent on the temperature and therelative dryness of the conveying air. By control of these two factors,which may be readily etfected in a manner believed obvious, an accuratedetermination and effecting of the desired moisture content of the finalprocessed pulp product may be had. I

From the flash drier, the pulp, accompanied by the 3 now hot moistcarrier air, is discharged into a cooling cyclone 14 where the hot moistair is separated from the pulp. It must be noted that the interval ofexposure of the pulp to the hot dry air stream in the flash drier isless than one minute and at no time does the temperature of the pulp atthe cyclone discharge exceed 130 F. As

a matter of fact, since the water flashes to steam at 212 F. and at thispoint that the heat of evaporation will cool the pulp fibers, it isdoubtful that the pulp temperature in the air stream Within the flashdrier ever exceeds 212 F. This flash-drying process is effective to drythe pulp to an optimum solids level of 75-95 percent dry.

The pulp, in fiber form on separation from the hot moist air and watervapor in the cyclone, is discharged to an air handling system whichdelivers the fiber to a twostation high density baler 15. At the firstor tamping station of the baler, the pulp is continuously delivered to abaler box until enough pulp is accumulated to form a bale, at which timethe flow of pulp is momentarily stopped. The baler box is then indexedunder a high compression ram system where the pulp is compressed to ahigh density by hydraulic rams to obtain a bale density in the range of45-65 pounds per cubic foot. Bales so compressed have been found to havelittle spring back and to retain their compression without strapping.The bale is then wrapped and/ or boxed for handling to warehouses or tocars for shipping. Strapping may be utilized but is not generallyrequired.

The resulting pulp bales as prepared for shipment are in the area of 90percent bone dry and are considerably reduced in volume from theconventional shipping form. Shipping economy is readily apparent andhandling difliculties are reduced to an absolute minimum in theemployment of the subject invention. There is substantially nodegradation of the pulp in storage or shipment.

The pulp so processed can be re-pulped with case. It can be broken downreadily in conventional slush pulpers and while there is some slightstrength lost in the drying and baling of the pulp, this can be readilyrestored by a slight beating or refining by the consumer.

The direct cost per ton of end product is substantially reduced in theemployment of the invention while its quality is increased. The systemis completely automatic and controlled and the only labor required isfor handling the baling and shipping operation. Two operators aresuflicient for the entire system.

, As a modification of the above described system, noting FIG. 2 of thedrawings, from the cyclone the fibers may be discharged into a felter20. The felter is a rectangular box, the bottom of which is provided bya continuously moving wire belt. The fibers fall to the felter in asnowstorm which settles 'as a thick mat on the moving wire belt. Thisbelt moves out of the felter between two rubber belts 21 to graduallyeffect a decrease of the mat thickness from about three to six inches toabout one-half to one inch. This provides a pre-compression of the pulpprior to baling. The pre-compressed mat is then delivered onto a lay-boy22 in continuous form so as to hairpin or fold back and forth on itselfto build up in layers. The lay-boy is gradually lowered as the layersare deposited until a predetermined amount is stacked, at which pointthe mat is cut. The stack is then moved from the lay-boy to a baling orindexing press 23 where the pulp is compressed to a bale of better than35 pounds per cubic foot density and then wrapped and/or boxed forremoval to storage and shipping.

The alternate modifications proposed may be selectively used dependingon the application intended. The staged drying process insures maximumquality products in either case.

From the above description it will be apparent that there is thusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is susceptible of modification in its form, proportions,detail con- 4- struction and arrangement of parts without departing fromthe principle involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has beendescribed in language more or less specific as to structural features,it is to be under tood that the invention is not limited to the specificfeatures shown, but that the means and construction herein disclosedcomprise but one of several modes of putting the invention into effect,and the invention is therefore claimed in any of its forms ormodification within the legitimate and valid scope of the appendedclaims.

Having thus described my invention, I claim:

1. A method of preparing pulp for shipment including the steps ofintroducing wood particles in a liquid carrier, agitating suchsuspension and draining to provide a suspension having a 15-20 percentsolids range, pressing said particles to reduce the water content andeffect a suspension having a 40-50 percent solids level, fluffing thepulp to separate it into fibers, flashing moisture in the process, andflash drying the pulp at moderate temperatures to a 75-95 percent drycondition.

2. A method of preparing pulp for shipment including, agitating anddraining a pulp suspension, subjecting the suspension so obtaining to acontinuous press operation to fiberize the pulp, grinding the pulp toreduce it to individual fibers and transmitting the pulp fibers insuspension in a pre-heated dry air stream to provide pulp which is 75-95percent dry.

3. A process of preparing pulp for shipment including the steps ofsuccessively agitating and pressing pulp in suspension, flufling thepulp in suspension to separate the pulp fibers, and introducing thefiberized pulp in suspension to a heated air stream to flash-dry thepulp to a substantially dry condition enabling compression of the fibersinto bale form.

4. A method of processing pulp for storage and shipment comprising thesteps of introducing pulp in a liquid carrier to provide a suspension ofpumpable consistency, subjecting the pulp in suspension to stagedshredding action and draining to reduce the suspension to a 40-50percent solids level, further treating the pulp to reduce it to anindividual fiber condition and introducing the pulp fiber to a dryheated air stream for an interval of one minut or less to separate thehot moist air from the pulp fiber to convert the pulp to an optimumsolids level facilitating baling of the pulp for shipment.

5. A method of processing pulp for shipment including the steps ofsubjecting a pulp suspension to staged dewatering and fiberizing action,flufling the pulp to separate the pulp fibers and flash moisturetherefrom, transmitting the fluffed pulp and subjecting it to a heatedair stream for less than one minute, the heated air stream relieving thepulp of moisture and maintaining it at a relatively low temperature, andseparating the pulp from the hot moist air stream to provide arelatively dry pulp capable of being baled and shipped without thedanger of pulp degradation in transit.

6. The method as set forth in claim 5 and further introducing theflash-dried pulp to a two stage baling press and pre-compressing andcompressing the pulp fiber to provide a bale having a density in therange of 45-65 pounds per cubic foot.

7. A method of preparing pulp for shipment including the steps ofsubjecting a pulp suspension to a fiberizing and de-watering action,fluffing and separating the pulp into fibers and, flash drying the pulpfiber for a period of less than one minute at relatively low temperatureranges.

8. A method as set forth in claim 7, and transmitting the flash driedpulp in fiber condition to a felter and compressing the fibers into :acontinuous mat, further compressing the mat so formed, hairpinning themat onto a layboy, separating the hairpinned mat portion on the layboyand compressing it to bale form to provide a pulp highly resistant tomicrobiological deterioration and readily handled and shipped.

9. A method of preparing pulp for shipment including the steps ofpassing a pulp suspension successively through a decker, a continuousscrew press and an attrition mill to fiberize the pulp in stagedfashion, fluff it and reduce it to a 40 to 50% dry condition,transmitting the pulp from the mill toa cyclone by means of a pre-heatedair stream flashing moisture from the fiberized pulp to dry it to anoptimum solids level, separating the hot moisture from the pulp in thecyclone and dropping the pulp fibers to a felter, pre-compressing thefiber delivered from the felter and stacking and baling the pulp soprovided.

10. A method of preparing pulp as set forth in claim 9 wherein the pulptemperature in the transmitting air stream is maintained at 212 or lessand the interval of time for transmission from the mill to the cycloneis substantially one minute.

11. A pulp handling system for conditioning pulp for storage or shipmentincluding, a series of fiberizing means connected to successivelyfiberize pulp in suspension and increase the solids content of thesuspension in stepped fashion, means in connected relation to saidfiberizing means for entraining the fiberized pulp in apre-heated airstream, means for receiving the pulp and the air stream which hasabsorbed moisture from the pulp for separating the pulp for baling, apress, and means interposed between said separating means andsaid pressfor matting and pre-compressing the pulp fiber obtaining to facilitatestacking and forming the pulp into fibrous bales.

12. Pulp conditioning apparatus including, means for successivelysubjecting a pulp in suspension to successively increasing fiberizingaction and incremental draining to increase the solids level 05 thesuspension, a felter, means for transmitting the fiberized pulp to thefelter and flash drying the pulp fiber in transmission, means fortransmit-ting the fiber in mat form from the felter and means forstacking the mat for compression and baling for shipment.

Stephenson: Preparation and Treatment of Wood Pulp, vol. 1, 1950,McGraW-Hill, pp. 782-800.

Cottrall: Introduction to Stuif Preparation for Paper Making, 1952,Charles Grifien & =Co., pp. 33-36.

11. A PULP HANDLING SYSTEM FOR CONDITIONING PULP FOR STORAGE OR SHIPMENTINCLUDING, A SERIES OF FIBERIZING MEANS CONNECTED TO SUCCESSIVELYFIBERIZE PULP IN SUSPENSION AND INCREASE THE SOLIDS CONTENT OF THESUSPENSION IN STEPPED FASHION, MEANS IN CONNECTD RELATION TO SAIDFIBERIZING MEANS FOR ENTRAINING THE FIBERIZED PULP IN A PRE-HEATED AIRSTREAM, MEANS FOR RECEIVING THE PULP AND THE AIR STREAM WHICH HASABSORBED MOISTURE FROM THE PULP FOR SEPARATING THE PULP FOR BALING, APRESS, AND MEANS INTER POSED BETWEEN SAID SEPARATING MEANS AND SAIDPRESS FOR MATTING AND PRE-COMPRESSING THE PULP FIBER OBTAINING TOFACILITATE STACKING AND FORMING THE PULP INTO FIBROUS BALES.